Addendum
fo3 said:
Perhaps there were other mechanisms on young earth too, but the DNA model was the only one that survived
Absolutely right! We know that before DNA, the genetic material was RNA, and before that, simpler molecules were used to transmit genetic information. Like humans and other animals, everything on earth, in the galaxy, in the universe, etc. is subject to natural selection, although it may not be apparent. DNA is the most effective carrier of genetic information, so it stayed once it happened to be made and was used. DNA is one atom different from RNA, so evolutionarily, it should not take too long for it to come along.
If DNA were perfect, there could be no evolution.
spidergoat said:
And besides, a system that didn't work very well wouldn't have survived very long, so thinking it's "too good" to be accidental is kind of a logical fallacy.
Systems that didnt work in the past don't just go out of style. Evolution is a continuum. There still remains more primitive metabolisms and genetic material on earth. The organisms that use these are fine with them, they, like the alligator, fall into their niche. We, as eukaryotes, were subjected to environmental stressors (need for large genomes) and DNA offered a better alternative, so once it formed due to a mutation or such, it stuck.
Roman said:
RNA may hold memory. They've extracted RNA from mice that have been trained to run a maze, then injected it into naive mice. The naive mice with the RNA injection did signifcantly better than the control in running the maze.
Scientists have taught planaria to avoid parts of a piece of glass (not an easy task, I hear), then ground up the planaria and fed them to other planaria. The new planaria avoided the same places.
First off, I cannot see one way in which any organism can somehow encode a memory into RNA. During the upregulation of genes that would encode for increased production of something like endorphins or whatever, the ability of the rats to simply run FASTER is the only variable that accounted for their enhanced performance. There is no thinkable way that RNA can encode a perceptual experience. If someone doesn't believe me, maybe a knowledge of general biology or neuroscience or biochemistry would help. The planaria reslt may be of the same consequence. What better source of nutrients for planaria could there be other than from planaria themselves? The assumption made in that experiment is absolutely ridiculous, if the experiment did in deed occur.
brerlee said:
Exactly what "science facts" are today considered "facts" have changed drastically from the recent past. Taxonomy has changed much from when I went to school, and at that time, the scientists "knew" their facts, but they keep changing them, year after year.
What scientists keep changing are not facts at all!!! Their systems of nomenclature have changed, yes, and the number of species they find in the world, of course. But scientists are continuously trying to find a way to 'fit in' all the information in the most sensible manner. Science itself is the means of identifying accurate data and making it fit together. Everything we see fits together perfectly, we just don't know how EVERYTHING fits. But we know MOST. Yes I know evolution is a theory, but it is not just a hypothesis. A hypothesis is a suggestion that is not verified. A THEORY is a generally accepted well-established and understood explanation for a process. It is the only way to describe what happened and has always been happening. A theory can NEVER EVER be PROVEN. They can be DISPROVEN, however. There are many theories that have been disproven, but evolution is the only theory of its kind that has NEVER BEEN DISPROVEN by a legitimate experiment.
brerlee said:
But, mutations are "accidental" (in frequency of occurrence) and most mutations are terminal (i.e. dead-end, for the species and the individual).
Yes, mutations are accidental, but thy are most necessary. Most mutations are not lethal, and if they are, there are many of other members of the population to survive. Even if they did all die out, there has been plenty of time for them to evolve again. Mutations in DNA for example, occur often in the human body. Many many times in each cell. If one base pair is copied wrong, then a similar amino acid will be encoded, not usually something completely different. This process is fast enough to provide for the chance of positive change, yet it is not usually lethal. Please try not to be completely ignorant of what most people consider common sense.
I hope this helps you guys
